Well, it's really a long time since I last was among native English speakers in a so-to-speak natural environment, but it astonishes me (depresses me?) not to have been aware of such expression. It does seem quite natural to me and indeed it must be since on both sides of the Atlantic you've offered promptly ready examples of it...

I had never heard of this Duke Ellington, I'll try to give a time to that link.

That "come" in "come rain, come shine" is a subjunctive comes natural to me.

In, for example, "come Friday", I wasn't certain how to interpret that "come" grammatically. But my dictionary labels it present subjunctive in those cases as well, and adds "fam."

My grammar, Svartvik, Sager: Engelsk universitetsgrammatik explains "come lunchtime" as "when lunchtime comes", without any mentioning of a subjunctive, under the heading "ellipsis". I prefer that explanation.

...When the majority of one's anger is intense, but a minority is not as intense, one could be mainly main angry. However, I think anger that is mulled for such time as to deliver itself of such interpretation is likely to have become frustration with age.